Serializes persistence metadata back to XML.
This class processes all object level tags that are store-agnostic.
However, it provides hooks for the subclasses to include store-specific
tags to be serialized both at <entity-mappings> and
<entity> level.

type

Return the type constant for the given object based on its runtime
class. If the runtime class does not correspond to any of the known
types then returns -1. This can happen for tags
that are not handled at this store-agnostic level.